WO 94/26722 generically discloses conversion of anthranilic acids to 2-thioquinazolinediones with isothiocyanates (see also: U.S. Pat. No. 3,755,582). WO 94/26722 discloses that the reaction is preferably performed in the presence of a base such as triethylamine.
WO 94/26722 also discloses conversion of 2-thioquinazolinediones to 2-chloro-4(3H)-quinzolinones using sulfuryl chloride (see also: U.S. Pat. No. 3,867,384). No mention is made of using phosgene for this transformation.
WO 94/26722 and U.S. Pat. No. 3,755,582 generically disclose 2-alkylthio-quinazolinones.
WO 94/26722 generically discloses the condensation of anthranilic acid esters with thiophosgene to form isothiocyanate esters. Similar procedures are disclosed in J. Heterocycl. Chem., (1990), 27, 407.
The preparation of 2,4-(1H,3H)-quinazolinediones from anthranilic acid and esters plus isocyanates is cited in J. Heterocycl. Chem., (1982), 19, 269.
EP-A-712849 discloses a process for the preparation of quinazoline-2,4-diones.